How to improve your VO2 max, and why some people barely can

What actually raises VO2 max

VO2 max, the maximum rate your body can use oxygen during intense exercise, rises mainly through structured training, and intensity matters. A 2013 meta-analysis pooling 334 people across 37 training studies found interval training raised VO2 max by an average of 0.51 liters per minute, and the study groups with the biggest responses improved roughly three times as much as the groups with the smallest responses, 0.87 versus 0.27 L/min (Bacon, Carter, Ogle and Joyner, PLoS ONE, 2013). That spread is the real story: the same program does not produce the same result in every person.

Why some people barely improve no matter how hard they train

Genetics heavily shapes how much any individual's VO2 max can rise from a given program. In the HERITAGE Family Study, 481 people across 99 families all completed the identical 20-week training plan, and the heritability of the training response itself was estimated at 47%, with a 21-gene panel separately explaining 49% of the variance in how much people improved (Sarzynski, Ghosh and Bouchard, The Journal of Physiology, 2016). People carrying few of the favorable gene variants gained an average of about 221 mL/min on the program; people carrying many of them gained about 604 mL/min, nearly three times as much, on the exact same plan. Exercise physiologist Martin Gibala has said roughly 40% of people show no measurable VO2 max improvement from a standardized moderate-intensity program over several months, though he notes higher intensity can close some of that gap: more vigorous, higher-intensity exercise "can potentiate or lead to greater improvements in VO2 max" (FoundMyFitness interview).

What doesn't reliably move the number

Marketed shortcuts have a weak track record here. No supplement has controlled-trial evidence of raising VO2 max the way structured interval training does, and products claiming otherwise are usually leaning on studies that are small, mixed, or not about VO2 max at all. Treat a VO2 max booster claim the way you would treat any supplement claim on this site: assume it is unproven until a trial on the actual product says otherwise. The same goes for recovery gadgets marketed as performance boosters: a device or ritual that helps you feel better between sessions is not automatically raising the physiological ceiling itself, and the two claims get blurred constantly in marketing copy.

How the genetics finding should change your approach, not your effort

The HERITAGE data is not a reason to stop training, it is a reason to stop comparing your results to someone else's. Two people can follow the identical interval program, track their numbers the same way, and land on opposite ends of that threefold gap in gains for reasons neither of them controls. The practical takeaway is to judge progress against your own baseline over 8 to 20 weeks rather than against a training partner, an influencer's before-and-after, or a number a wearable estimated for someone else entirely.

What a smartwatch VO2 max number actually tells you

Wearables estimate VO2 max from heart rate, pace and activity data rather than measuring oxygen use directly, and that estimate is less precise than a lab test with a metabolic cart, according to Geisinger pulmonologist Dr. Sudheer Penupolu. It is useful for tracking your own trend over months, not as a clinically precise figure to compare against someone else's lab-tested number. For a sense of what a good number looks like by age and sex, see what is a good VO2 max? and what counts as a good VO2 max for your age.

Why it is worth the effort anyway

Cardiorespiratory fitness is one of the strongest mortality markers studied. In a Cleveland Clinic cohort of 122,007 adults who took a treadmill test between 1991 and 2014, people with the lowest fitness had more than five times the mortality risk of the fittest group, a larger gradient than smoking or diabetes carried in the same study (Mandsager et al., JAMA Network Open, 2018). That is observational data, so it shows a strong association with survival rather than proof that raising your personal number by any specific amount adds a specific number of years. Still, it is a real reason to keep training even if your genetics cap how far your number climbs.

Our take

Structured intervals beat steady cardio alone for raising VO2 max, on average. But how much you personally gain is shaped heavily by genetics, and a real share of people see little change on a standard program, which is worth knowing before you blame your effort. No supplement has solid evidence of moving the number. Train consistently, mix in genuine high-intensity efforts, and judge progress by your own trend over months rather than a smartwatch figure or someone else's result.

This is general information, not medical advice. Talk to a clinician before changing anything, especially if you are pregnant, nursing, or managing a condition.